Automatic tracking control apparatus for maintaining alignment of a moving web



March 5, 1968 EM 3,371,916

. J. JAEGER AUTOMATIC THACKI c ROL APPARATUS FOR MAINTAINING ALIGNM or A MOVING WEB Filed Sept. 5, 1965 2 Sheets -Sheet 1 INVENTORS I WALTER J. JAEGER & I CHESTER G. JONES THEIR ATTORNEYS 3,371,916 AlNING W. J. JAEGER ETAL March 5, 1968 AUTOMATIC TRACKING CONTROL APPARATUS FOR MAINT ALIGNMENT OF A MOVING WEB 2 Sheets-Sheet 2 Filed Sept. 5, 1965 INVENTORS WALTER J. JAEGER 81 CHESTER G. JONES THEIR ATTORNEYS United States Patent Ofiice 3,371,916 AUTOMATIC TRACKING CONTROL APPARATUS FOR MAINTAINING ALIGNMENT OF A MOVING WEB Walter J. Jaeger and Chester G. Jones, Kettering, Ohio, assignors to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Filed Sept. 3, 1965, Ser. No. 484,815 4 Claims. (Cl. 226-17) ABSTRACT OF THE DISCLOSURE An automatic tracking control apparatus for maintaining alignment of a moving web which utilizes correction rollers having axes of rotation positioned at an acute angle relative to the intended direction of travel of the web, so as to shift the web laterally to restore it to the intended direction of travel. The apparatus also includes sensing rollers having axes of rotation positioned at an acute angle relative to the intended line of direction so as to detect lateral shifts in the web and to actuate the appropriate correction roller.

This invention relates to a device for maintaining alignment of a moving web in the direction of travel along its length and is generally applicable for controlling lateral shifting of the inked ribbon used in high-speed printers such as those used with electronic data-processing equipment.

In a high-speed printer of a known variety, the type fonts are arranged in parallel arrays circumferentially on a cylindrical drum whose axis lies parallel to the plane of the paper to be printed upon. Printing hammers of the machine, which are located opposite their respective arrays, are located beneath the drum, and the inked ribbon is located adjacent to and passes beneath the drum. The paper to be printed upon is positioned between the ribbon and the hammers, and both paper and ribbon are fed past the hammers in a direction which is perpendicular to the axis of the cylindrical dr-um. This drum, with the type font thereon, is rotated continuously at a high speed, and, at the proper instant, a printing hammer is driven upwardly to strike the back of the paper and drive it and the ribbon against a predetermined character on the drum to thereby print the character on the paper.

Under such operating conditions, the ribbon is subjected to severe use due to .the combined action of the hammer impact and the simultaneous sliding rotary motion of the cylindrical drum having the type fonts thereon. This severe use has a tendency to stretch and distort the fabric of the ribbon, making the ribbon diflicult to control in feeding, and, as a result, the ribbon tends to shift laterally or skew from its intended direction of travel along its length. This lateral shifting results in character printing omissions due to absence of the inked ribbon between the affected characters on the drum and the paper.

The present invention provides a device for maintaining alignment of the inked ribbon so as to eliminate such printing omissions. The device utilizes a frame member which is positioned in the high-speed printer at a point past the printing station. First and second sensing members are positioned on the frame member to receive the width of the ribbon therebetween and to detect the lateral shifting of the inked ribbon as it passes the printing station on its way to one of the rollers on which the ribbon is wound after use. The means for winding and rewinding the ribbon on rollers as it is moved past the printing station in the high-speed printer are known and do not form a part of this invention.

In moving over the frame member and between the sensing members positioned thereon, the lateral edges of the ribbon do not engage the sensing members as long as the ribbon movement remains aligned in the intended direction of travel along its length. However, when the ribbon begins to shift laterally to one side or the other, the lateral edge of the ribbon engages the pertaining sensing means and actuates it and thereby causes an operation of the pertaining restoring means to which it is operably connected.

Also included in the present invention are a first and a second ribbon-restoring means, which are positioned on said frame member and spaced from said first and second sensing means, respectively, along said direction of travel and which are also adapted to receive the width of the ribbon therebetween. Each restoring means has a roller member adapted to be moved into engagement with the ribbon when actuated by the particular sensing means operably connected therewith. When moved into engagement with the ribbon, the restoring means is effective to drag the ribbon in a direction opposite to the direction in which the ribbon was laterally shifting when the sensing means was actuated and thereby maintain ribbon alignment.

Each sensing means, when actuated, is effective to energize the restoring means on the opposite lateral edge of the ribbon. For example, when the ribbon is shifting laterally to the left, the sensing means on the left lateral edge of the ribbon is actuated to energize the restoring means located on the opposite, or right, side of the width of the ribbon. The restoring means on the right side of the ribbon then engages the ribbon between its lateral edges and drags the ribbon to the right to restore it in the direction of travel until such time as the left lateral edge of the ribbon disengages the left sensing means, thereby de-energizing the right restoring means.

The other sensing and restoring means are utilized in a similar manner to return the ribbon to the left when the ribbon shifts laterally to the right. With a sensing means and a restoring means on each of the lateral edges of the ribbon, the ribbon alignment can be accurately controlled.

Each restoring means utilizes a pivotal member having on one end thereof a canted roller which engages the ribbon between the lateral edges thereof to move or drag the ribbon in a direction which corrects the lateral shifting thereof.

Each sensing means also uses a pivotal member having a canted roller, which member pivots to permit critical adjustment thereof, which in turn allows accurate sensing of the lateral shifting of a sheer material like an inked ribbon.

One of the prior-art means for maintaining alignment of an inked ribbon in a high-speed printer utilizes a shifta-ble bar over which the ribbon travels. By positioning the bar, tension can be brought to one side or the other of the ribbon to steer the ribbon and thereby minimize its lateral shifting. Sensing the lateral shifting of the ribbon is performed by allowing the ribbon to close a microswitch directly as the ribbon shifts laterally of its intended direction. This construction requires a complicated mechanism and also requires the ribbon to be under tension.

Another prior-art means for maintaining alignment of an inked ribbon in a high-speed printer consists of reinforcing the lateral edges of the ribbon with a stiff strip having therein perforations which are engaged by driving and guiding sprockets. Two pairs of such sprockets are used, with one pair ahead of the other pair behind the printing zone. Both driving and guiding sprockets in each pair are coupled on one shaft, with the driving sprocket being fixed to rotate therewith, while the guiding sprocket Patented Mar. 5, 1968 is axially movable and spring-loaded on the shaft away from its companion driving gear in order to apply lateral tension to the ribbon. In this manner, the movement of the ribbon is constrained to a desired path.

The following are the objects of the present invention:

(a) To provide an automatic tracking control apparatus for maintaining alignment of a moving web moving in the direction of its length.

(b) To provide a sensitive, dependable, easily adjustable, automatic tracking control apparatus for maintaining alignment of an inked ribbon in a high-speed printer.

These and other objects and advantages will become more readily understood in connection with the following description and the drawings, in which:

FIG. 1 is a general perspective view of the automatic tracking control apparatus of this invention in a typical application at the printing station of a high-speed printer;

FIG. 2 is a plan view of the tracking control apparatus taken along the line 22 of FIG. 1 and showing the placement of the means for sensing the lateral shifting of the ribbon and the means for restoring the ribbon to maintain it in proper tracking;

FIG. 3 is a sectional view taken along the line 33 of FIG. 2, showing the arrangement of the sensing and correction rollers of the sensing and restoring means, respectively;

FIG. 4 is a plan view of the underside of the plate over which the ribbon travels, showing the gripping rollers which are part of the restoring means;

FIG. 5 is an end view of the apparatus shown in FIG. 4, particularly showing how the correction roller of the restoring means is operatively connected to its actuating solenoid; and

FIG. 6, on the sheet with FIGS. 1, 2, and 3, is a general schematic diagram of the wiring of this invention, with the sensing and restoring means thereof illustrated in block form.

In FIG. 1, the automatic tracking apparatus, generally designated 10, is shown positioned at the printing station of a high-speed printer 12. The printer has side frames 14 (only one of which is shown), between which frames the tracking apparatus is mounted. The printing station also includes known ribbon windup rollers 16 and 16a, and a type drum 18, which are suitably mounted between the side frames 14. The printing hammers, represented in block form 20, are shown positioned generally beneath the type drum 18, which is rotated at a high speed and which has the printing characters thereon. The printing ribbon 22 is positioned between the type drum 18 and the paper 24, which receives the printed record. As the drum 18 is rotated, a printing hammer is fired at the precise instant and pushes the paper 24 and the ribbon 22 against a preselected character on the revolving type drum 18 to print the character on the paper 24. As detailed functioning of the printing apparatus does not form a part of this invention, it is described herein only generally, and a more detailed explanation thereof may be obtained by reference to United States Patent No. 2,787,210, which issued to Francis H. Shepard, Jr., on April 2, 1957.

The frame of the tracking apparatus as shown in FIGS. 1 through 5 comprises tubular rods 26 and 28, which are slidably inserted in aligned spaced apertures in blocks 30, which are detachably retained to the side frames 14 by screws 32. The frame also includes generally U-shaped members 34 and 36, each having a flat section 38 and legs 40 and 42 integrally joined therewith. The legs 40 and 42 have aligned apertures therein to receive the tubular rod 26, as shown in FIGS. 4 and S. The portions of the legs 40 and 42 which are adjacent to the rod 28 have arcuate notches therein, in which a portion of the periphery of the rod 28 is positioned to thereby prevent rotation of the U-shaped members 34 and 36 relative to the rod 26. Each of the legs 40 has a bushing 44 secured to one side thereof, as shown in FIGS. 4 and 5, and each bushing is provided with a set screw 46 to slidably and adjust- A ably fix the U-shaped members 34 and 36 on the rods 26 and 28 to adjustably receive the width of the ribbon 22. The ribbon 22 slides over the flat sections 38 in the direction A shown in FIGS. 1 and 2 when the tracking apparatus is effective for maintaining the ribbon in proper alignment.

The sensing means, generally designated 48 and 58, are positioned on the U-shaped members, respectively, in spaced relation to each other and are adapted to receive the width of the ribbon 22 therebetween, as shown in FIG. 2. Each sensing means 48 and 50 comprises a roller 52, which is rotatably mounted and retained on a shaft 54, which is secured to one end of an arm 56. The other end of the arm 56 is secured to one side of a block 58, which is pivotally secured to the fiat section 38. The opposite side of the block 58 engages an actuating lever 60 of a standard micro switch 62 of the sensing means 50, which switch is secured to the fiat section 38.

The sensing means 48 and 50 are identical except that the arm 56 of each sensing means is arranged to rotate in opposite directions. For example, as the ribbon 22 moves in the direction A shown in FIG. 2, it glides over the flat sections 38 and under U-shaped resilient wire ribbon retainers 64, which are secured to the flat sections 38. As long as the ribbon 22 moves solely in the direction A, it does not engage either of the sensing means 48 or 50; however, if the ribbon tends to shift laterally towards the left, for example, as viewed in FIG. 2, while moving generally in the direction A, the left lateral edge 66 of the ribbon engages the roller 52, causing it to rotate. Due to the fact that the axis of rotation of the roller is canted at an angle of approximately forty-five degrees with respect to the direction of travel A, the roller 52 is dragged by the ribbon, causing the arm 56 and the block 58 of the sensing means 48 to be rotated counter-clockwise. As the block 58 rotates, it moves the actuating lever 60 to close a standard micro switch 70 of the sensing means 48, and thereafter the block 58 abuts against a stop 68, which restricts its rotation.

When the switch 70 of the sensing means 48 is closed, it completes a circuit to the ribbon restoring means 72 shown in block form in FIG. 6. The restoring means 72, which will be described in detail hereinafter, is effective to move the ribbon 22 to the right, as viewed in FIGS. 2 and 6, and thereby restorethe ribbon to a desired central position. When the ribbon has returned to the central position shown, the left edge 66 of the ribbon is moved out from under the roller 52, causing the sensing means 48 to be returned to the home position, wherein the switch 70 is opened, thereby de-energizing the restoring means 72.

When the ribbon 22 tends to shift laterally to the right, as shown in FIGS. 2 and 6, the edge 74 of the ribbon engages the roller 52, and the arm 56 and the block 58 of the sensing means 50 are rotated clockwise. As the block 58 rotates, it moves the actuating lever 60 to close the micro switch 62 by the technique previously explained. Closing of the switch 62 is effective to energize the restoring means 76, positioned on the opposite side of the ribbon 22.

When the restoring means 76 is energized, it drags the ribbon 22 to the left, as viewed in FIGS. 2 and 6, until the right edge 74 of the ribbon is disengaged from the roller 52 of the sensing means 50, at which time the switch 62 opens to de-energize the restoring means 76. When the rollers 52 of the sensing means 48 and 50 are clear of their respective ribbon edges 66 and 74, the spring-loaded levers 60 of the pertaining rnicro switches return the blocks 58 to the home position, shown.

By this construction, the sensing means 48 and 50 can be actuated with little force or tension on the ribbon and can be critically adjusted for the amount of lateral displacement of the ribbon necessary to actuate the pertaining sensing means. The adjustment is made simply by shifting the U-shaped members 34 and 36 on the rods 26 and 28 to obtain the desired spacing between rollers 52.

The rollers 52 are ground for concentricity and are made of wear-resistant high-friction materials such as rubber or polyurethane, and their perimeters are adjusted to provide a clearance of about 1 /2 to 2 /2 thousandths of an inch between the sections 38 and the rollers 52 when an inked ribbon having a thickness of about .003 inch is used.

The blocks 58 (to which the rollers 52 and the arms 56 are adjustably secured by screws 78 shown in FIG. 5) are pivotally mounted to the flat sections 38 as follows: a stud 80 has one end welded to the section 38, and a spring 82 is positioned on the stud 80 to urge the flanged bushing 84 away from the section 38. The bushing 84, with the stud 80 passing therethrough, is inserted into an aperture in the block 58, and a stop nut 86, threadedly secured to the remaining end of the stud 80, is used to maintain the assembly in the position shown. By varying the tension on the spring 80 via the stop nut 86, and by adjusting the screws 78, different clearances between the rollers 52 and their related sections 38 can be readily obtained.

The ribbon-restoring means, generally designated 72 and 76 and shown in FIG. 5, for example, are similar in construction, and therefore a discussion of only one restoring means, 72, will follow.

The restoring means 72 comprises a correction roller 88, which is rotatably mounted and retained on a shaft 90, which is fixed to one arm 92 of a multi-armed lever 93, which is pivotally secured to a block 94, which is in turn secured to the fiat section 38. Another arm '96, of the lever 93 is pivotally pinned to the slotted operating arm 98 of a solenoid 100, which is secured to the flat section 38.

The fiat section 38 is provided with a slot 102, which is in alignment with a grip roller 104, which is rotatably mounted on an arm 106, secured to the fiat section 38. The periphery of the grip roller 104 is positioned in the slot so as to enable the ribbon 22 to be gripped between it and the correction roller 88 when the solenoid 100 is energized upon the closing of the switch 70 of the sensing means 48.

It should be noted that the axes of both rollers 88 and 104 are canted with respect to the movement of the ribbon 22 in the direction A, as shown in FIG. 2, and the directions of the axes of rotation are such as to make an acute angle '105 (FIG. 2) with the direction ofmovement A. When the solenoid 100 is energized, the lever 93 moves clockwise, as xiewed in FIG. 5, and forces the correction roller 88, carried thereby, against the grip roller 104 to grip the ribbon 22 therebetween. As the grip roller 104 is canted, it has a tendency to drag the ribbon 22 to the right, as viewed in FIG. 2. The ribbon 22 moves to the the right until its left edge 66 is pulled out of engagement with the roller 52. Upon disengagement of the edge 66 from the roller 52, the switch 70 of the sensing means 48 is opened to de-energize the solenoid 100 of the restoring means 72, permitting a spring 108 on the solenoid arm 98 to return the multi-arm lever 93 to the ribbon-releasing position, shown in FIG. 5.

The restoring means 76 is similar in construction to the restoring means 72; however, the multi-arrned lever 112 and the correction roller 110 rotatably secured thereto rotate counter-clockwise, as viewed in FIG. 5, to force the ribbon 22 into engagement 'with a grip roller 114 upon energization of a solenoid 116. The grip roller 114 is similar to the grip roller 104. The solenoid 116 of the restoring means 76 is connected in series with the switch 62 of the sensing means 50, as shown in FIG. 6. One electrical lead of each said solenoid is grounded, and the other lead is connected in series with one terminal of the switches 70 and 62 of the pertaining sensing means 48 and 50, respectively, as shown. The remaining terminals of the switches 62 and 70 are connected to a source of voltage V, one side of which is also grounded.

The leads shown in the wiring diagram of FIG. 6 may be conveniently placed in the tubular rods 26 and 28, if

6 desired, to provide a neat wiring arrangement, and covers 118 may be secured to the frame by fastener and bracket means 120 (FIG. 3) to provide protection for the sensing and restoring means.

It should be noted that the sensing and restoring means means of this invention operate only when the ribbon is traveling in the direction A, as shown in FIGS. 1, 2, and 6. When the ribbon 22 travels opposite to the direction A to wind on the other windup roller 16a, the sensing and restoring means are ineffective due to the cant of the rollers 52, 88, and 110. As an added precaution, the wiring circuit shown in FIG. 6 can be incorporated in the circuit for the ribbon windup roller 16, so that electrical energy is supplied to the circuit only when the windup roller 16 is energized for transporting the ribbon 22 in the direction A shown in FIG. 1. It is necessary to maintain alignment of the ribbon 22 only when it is traveling in one direction, as this one alignment is satisfactory to maintain the ribbon 22 in good form on the windup roller '16 for rewinding in the direction opposite to A and onto the other windup roller 16a.

It will be obvious that variations may be made to the specific embodiment shown herein without departing from the spirit of the invention as reflected in the scope of the following claims.

What is claimed is:

1. A device for maintaining alignment of a moving web in the direction of travel along its length, comprising:

a frame member over which said web moves,

first and second sensing means positioned in spaced relation on said frame member and adapted to receive the width of said web therebetween,

each said sensing means being adapted to be actuated and deactuated upon engagement and disengagement respectively with a lateral edge of said Web as it shifts laterally of said direction of travel,

first and second restoring means positioned on said frame member and spaced from said first and second sensing means respectively along said direction of travel and adapted to receive the width of said web therebetween, and

means operatively connecting said first sensing means with said second restoring means and operatively connecting said second sensing means with said first restoring means,

each said restoring means being energized and deenergized when the pertaining sensing means to which it is operatively connected is actuated and deactuated respectively,

each said restoring means having a movable member adapted to be moved from an inoperative position to an operative position upon actuation of its pertaining sensing means to engage said web between the lateral edges thereof and to shift said web lateral- 1y away from its pertaining sensing means,

each said sensing means being pivotally mounted on said frame member and comprising roller means having an axis of rotation whose direction is at an acute angle to said direction of travel.

2. A device for maintaining alignment of a moving web in the direction of travel along its length, comprising:

a frame member over which said web moves,

first and second sensing means positioned in spaced relation on said frame member and adapted to receive the width of said web therebetween,

each said sensing means being adapted to be actuated and deactuated upon engagement and disengagement respectivelywith a lateral edge of said web as it shifts laterally of said direction of travel,

first and second restoring means positioned on said frame member and spaced from said first and second sensing means respectively along said direction of travel, and adapted to receive the width of said web therebetween, and

means operatively connecting said first sensing means with said second restoring means and operatively connecting said second Sensing means with said first restoring means,

each said restoring means being energized and deenergized when the pertaining sensing means to which it is operatively connected is actuated and deactuated respectively,

each said restoring means having a movable member adapted to be moved from an inoperative position to anoperative position upon actuation of its pertaining sensing means to engage said web between the lateral edges thereof and to shift said web laterally away from its pertaining sensing means,

each said sensing means comprising a sensing member pivotally mounted on said frame member and having an arm extending therefrom, roller means rotatably mounted on said arm with the axis of rotation thereof having a direction at an acute angle to said direction of travel, the periphery of said roller means being spaced from said frame member so as to be rotated by said moving web as it passes therebetween,

and switch means adapted to be actuated by said sensing member as the sensing member is pivoted in said direction of travel when a lateral edge of said moving web shifts laterally of said direction of travel and engages said roller means.

3. An automatic tracking control apparatus for maintaining alignment of a moving ribbon in a predetermined direction along its .length, comprising:

a frame over which said ribbon moves,

first and second sensing means mounted in spaced relation on said frame and adapted to receive the width of said ribbon therebetween,

each said sensing means comprising a sensing member pivotally mounted on said frame between operative and inoperative positions and having an arm extending therefrom,

a roller rotatably mounted on the free end of said arm with the axis of rotation of said roller being located at an acute angle to said predetermined direction,

the periphery of said roller being spaced from said frame so as to be rotated by said ribbon as said ribbon moves therebetween when shifting laterally of said predetermined direction, said ribbon when shifting laterally also being effective to pivot said sensing member in said predetermined direction to said operative position,

and switch means operatively connected to the sensing member so as to be closed upon the pivoting of said sensing member to said operative position and to be opened upon the return of said sensing member to said inoperative position,

said apparatus further comprising first and second restoring means positioned on said frame and spaced from said first and second sensing means respectively along said predetermined direction, and adapted to receive the width of said ribbon therebetween,

each said restoring means comprising a grip roller rotatably mounted on one side of said frame, said frame having a slot therein to receive at least a portion of said periphery of said grip roller,

a lever pivotally mounted on said frame and adapted to be moved between inoperative and operative positions,

a correction roller rotatably mounted on one end of said lever,

said grip and correction rollers each having an axis of rotation which is located at an acute angle to said predetermined direction, said grip and correction rollers being arranged to grip said ribbon between the peripheries thereof when said lever is in said operative position,

and solenoid means to move said lever to said operative position upon the closing of the pertaining said switch means in the pertaining said sensing means and to move said lever to said inoperative position upon the opening thereof,

and means operatively connecting said switch means of said first sensing means with said solenoid means of said second restoring means, and operatively connecting the said switch means of said second sensing means with said solenoid means of said first restoring means,

each said correction roller when in said operative position being effective to engage the said ribbon between the lateral edges of the width thereof and move said moving ribbon laterally in a direction away from the pertaining sensing means to which it is operatively connected until the last-named sensing means is returned to its inoperative position upon disengagement from said ribbon.

4. In combination, a high-speed printing machine of the variety comprising a printing station having printing hammers and type font, means for moving a printing ribbon past said printing station, and a device for maintaining alignment of said printing ribbon in the direction of travel along its length past said printing station, said device comprising:

a frame member over which said ribbon moves, sensing means pivotally mounted in spaced relation on said frame member and adapted to receive the lateral edges of the width of said web therebetween,

each said sensing means being adapted to be pivoted from an inoperative position to an operative position by the dragging action of the said moving web when in engagement therewith due to a lateral shifting of the web away from said direction of travel and towards the pertaining said sensing means,

restoring means positioned in spaced relation on said frame member and adapted to receive the width of said web therebetween with each said restoring means being positioned along said direction of travel from one of said sensing means and spaced therefrom, and

means for operatively connecting each said restoring means with the said sensing means located on the opposite lateral edge of the width of said web so as to energize and deenergize the pertaining restoring means when the pertaining sensing means is moved into said operative and inoperative positions, respectively,

each said restoring means having a roller member adapted to be moved from an inoperative position to an operative position in which it engages said moving web between the lateral edges thereof and is effective to shift the moving web laterally away from the pertaining sensing means to which it is operatively connected to thereby restore said last-named sensing means to said inoperative position,

each said sensing means comprising a movable member having a roller on one end thereof adapted to be moved into said operative position by said dragging action of the moving web when in engagement therewith,

said roller member of each said restoring means and said roller of each said sensing means having an axis of rotation whose direction is at an acute angle to said direction of travel.

References Cited UNITED STATES PATENTS 642,141 1/1900 Lyon 226-15 1,769,687 7/1930 Hamilton 226-l7 2,451,343 10/1948 Kunzle 22617 X 2,947,057 8/1960 Meagher et al 226-17 X 3,057,293 10/1962 Zurowski 226-15 X 3,147,898 9/1964 Huck 226-17 ALLEN N. KNOWLES, Primary Examiner. 

